Method for obtaining a wax from a pyrolysis residue

Abstract

The invention relates to a method for obtaining a wax from a pyrolysis residue, having the steps of (a) providing the pyrolysis residue, wherein the pyrolysis residue comprises the wax and a solid material, and the solid material comprises an inorganic salt, a ceramic raw material, an asphaltene, tar, and / or coke, (b) adding a solvent to the pyrolysis residue in order to obtain a solid material-enriched mixture comprising the solid material and the solvent, said wax being at least partly dissolved in the solvent, (c) separating at least one part of the solid material from the solid material-enriched mixture in order to obtain a solid material-depleted mixture, and (d) separating at least one part of the wax from the solid material-depleted mixture. The invention additionally relates to a device for obtaining a wax from a pyrolysis residue using said method.

Description

[0001] Process for obtaining a wax from a pyrolysis residue

[0002] The invention relates to a method and a device for obtaining a wax from a pyrolysis residue.

[0003] Processes for pyrolyzing a starting material, especially a plastic, are known in the art. The focus is usually on obtaining products from a gaseous fraction of the resulting pyrolysis product. The pyrolysis residue is generated as a waste product and is usually used for energy recovery.

[0004] Such a pyrolysis process is disclosed, for example, in JPH 09125073 A. A waste plastic is pyrolyzed in a pyrolysis reactor to obtain a pyrolysis product comprising a gaseous fraction and a pyrolysis residue. The gaseous fraction is cooled and condensed to a product oil. Various fractionated oils can be obtained from this product oil by distillation. A solvent, which can be a product oil or a fractionated oil, is added to the pyrolysis residue. Alternatively, kerosene, light oil, heavy oil, benzene, toluene, or xylene can be used as the solvent. Part of the pyrolysis residue is intended to dissolve in the solvent, which should enable the separation of a solid, coke-containing fraction contained in the pyrolysis residue. The solvent, along with the part of the pyrolysis residue dissolved in it, is then returned to the pyrolysis reactor for further pyrolysis.

[0005] WO 2023 / 285472 A2 describes a process for the pyrolysis of plastic waste, whereby the resulting pyrolysis gas is separated from solids (e.g., coke). The pyrolysis gas is subsequently condensed to obtain a pyrolysis oil fraction, from which a wax is then separated.

[0006] WO 2017 / 168165 A1 relates to a process for producing a lubricant by pyrolysis of a plastic. WO 2021 / 115982 A1 describes a process for obtaining aliphatic hydrocarbons from a liquid hydrocarbon stream. US 2021 / 0332300 A1 is directed to a process for converting plastic waste into recycled products for use in the polymerization of propylene.

[0007] WO 2009 / 086107 A2 provides a process for converting heavy oil into lower-boiling hydrocarbon products. US 2009 / 0057192 A1 relates to a process for producing an improved feed stream for a deasphalting process. US 3,720,599 A discloses a process for dewaxing petroleum.

[0008] Despite the processes known from the prior art, the utilization of pyrolysis residues, especially from plastic pyrolysis, has not yet been satisfactorily resolved. Therefore, there is a need for alternative, improved processes for the utilization of such pyrolysis residues. It is an object of the invention to provide such a process.

[0009] The present invention relates to a process for obtaining a wax from a pyrolysis residue, comprising the steps

[0010] (a) providing the pyrolysis residue, wherein the pyrolysis residue comprises the wax and a solid, preferably wherein the solid comprises an inorganic salt, a ceramic raw material, an asphaltene, a tar and / or a coke,

[0011] (b) adding a solvent to the pyrolysis residue to obtain a solids-rich mixture comprising the solid and the solvent, wherein the wax is at least partially dissolved in the solvent,

[0012] (c) separating at least a portion of the solid from the solid-rich mixture to obtain a solid-lean mixture, and

[0013] (d) separating at least a portion of the wax from the low-solids mixture.

[0014] The invention is based on the finding that a pyrolysis residue, in particular a pyrolysis residue obtained by plastic pyrolysis, represents a valuable source of wax. The process according to the invention not only makes it possible to recover at least a portion of the wax contained in the pyrolysis residue, but also at least a portion of the solid contained in the pyrolysis residue. Consequently, the process can reduce the burden on the environment by lowering greenhouse gas emissions and reducing the amount of waste. Overall, resource consumption can be significantly reduced and the circular economy strengthened, which can also bring economic benefits. In particular, the resulting wax can represent a sustainable alternative to wax obtained directly from petroleum.

[0015] The pyrolysis residue can be obtained by pyrolyzing a plastic, especially a waste plastic. The pyrolysis can be carried out in a pyrolysis reactor, preferably at a temperature of 300 to 500 °C, especially 350 to 450 °C. This allows a good balance between cost-effectiveness and process efficiency to be achieved.

[0016] The pyrolysis can be thermal pyrolysis (i.e., thermal cracking without the addition of a catalyst) and / or catalytic pyrolysis (i.e., catalytic cracking). Thermal pyrolysis is preferred to avoid any contamination of the wax and / or the solid due to catalyst components.

[0017] Pyrolysis can be carried out largely in the absence of oxygen, especially in an inert atmosphere, such as nitrogen. A lack of oxygen or the absence of oxygen can prevent complete combustion and cause a polymer contained in the plastic to be cleaved or depolymerized.

[0018] The plastic preferably comprises a polyolefin and / or a polystyrene (PS), wherein the polyolefin may comprise a polyethylene (PE) and / or a polypropylene (PP). The plastic preferably comprises the polyolefin and / or the polystyrene in an amount of at least 65% by weight, more preferably at least 70% by weight, in particular at least 90% by weight, based on the total weight of the plastic. This makes it possible to obtain a pyrolysis residue which comprises a significant proportion of an aliphatic hydrocarbon (or a mixture of several aliphatic hydrocarbons), i.e., a significant proportion of the wax.

[0019] The plastic preferably comprises at least 20% by weight of the polyolefin, more preferably at least 50% by weight, even more preferably at least 70% by weight, in particular at least 90% by weight, based on the total weight of the plastic. With increasing polyolefin content, the amount of wax obtained using the process according to the invention can be increased, which can improve the economics of the process. The plastic can comprise another polymer from the group consisting of thermoplastics, thermosets and / or elastomers, in particular an acrylonitrile-butadiene-styrene copolymer (ABS), a polyvinyl chloride (PVC), a polyamide (PA) and / or a polyester.

[0020] Before pyrolysis, the plastic can be plasticized, for example, in a mixer, especially in an extruder. The plastic is preferably heated to a temperature of at least 120°C to plasticize it, more preferably to a temperature of 200 to 500°C, even more preferably 400 to 470°C. The subsequent pyrolysis can then be carried out more energy-efficiently and in a shorter time. The plastic can also be degassed in the extruder to produce a uniform mass without gas inclusions, so that a homogeneous pyrolysis product can be obtained by the subsequent pyrolysis.

[0021] Before pyrolysis, a diluent can be added to the plastic, in particular to the plasticized plastic, to reduce its viscosity. The diluent is preferably added to the plastic in an amount of at least 5% by weight, more preferably at least 9% by weight, based on the total weight of the plastic. The ratio of plastic to diluent is preferably at least 1:4, preferably at least 1:9. By adding the diluent to the plastic, the mobility of polymer chains can be increased at a given temperature, so that the heat input into the plastic can be improved during pyrolysis. Furthermore, due to the viscosity reduction, the risk of overheating of plastic in wall regions of the pyrolysis reactor can be reduced, since this is usually heated by a heating device arranged near an outer wall of the pyrolysis reactor.The risk of coking of the plastic during pyrolysis can also be reduced by reducing the viscosity.

[0022] By adding the diluent to the plastic, its viscosity can preferably be reduced by at least 30%, more preferably by at least 50%, particularly preferably by at least 80%, relative to the viscosity of the plastic without diluent under the same measurement conditions, in particular at a temperature in the range of 180 to 240 °C. This can improve the pumpability of the plastic, which can facilitate its processing.

[0023] When the diluent is added, the plastic preferably has a temperature of at least 120°C, more preferably a temperature of 150 to 300°C, in particular of 200 to 300°C. Alternatively or additionally, the diluent can be heated to a temperature of preferably at least 120°C, more preferably at least 150°C, in particular to a temperature of 200 to 300°C, before being added to the plastic. By increasing the temperature of the plastic and / or the diluent, the diluent can be mixed into the plastic more quickly and efficiently. The subsequent pyrolysis can also be carried out more quickly and in a more energy-efficient manner.

[0024] The diluent can be added to the plastic using a dosing device. The dosing device can comprise a metering device, such as a metering pump. For example, the plastic, in particular the plasticized plastic, can be fed to a mixer, e.g., a static mixer, and mixed there with the diluent. If the plastic is plasticized in an extruder, the diluent can be added directly in the extruder. For this purpose, the dosing device can be arranged, for example, in the compression zone or mixing zone of the extruder.

[0025] The diluent can comprise a hydrocarbon selected from an alkane, a cycloalkane and / or an aromatic. By pyrolysis, such a diluent can be converted into a gaseous and / or liquid product which can be at least partially separated from the pyrolysis residue and further utilized. The diluent preferably comprises at least a portion of a liquid fraction of the pyrolysis residue. This can be separated, for example, in a hydrocyclone. Alternatively or additionally, the diluent can comprise a fraction obtained from crude oil, in particular a heavy oil. The heavy oil can be an oil obtained from petroleum in a petroleum refinery, e.g. a residual oil from a pyrolysis plant. The heavy oil preferably has a proportion of an aromatic hydrocarbon of at least 25% by weight, based on the total weight of the heavy oil.

[0026] The diluent preferably has a boiling point (or a lower end of a boiling range) of at least 300°C, in particular at least 350°C. This prevents the diluent from evaporating immediately after a mixture of plastic and diluent is introduced into the pyrolysis reactor; instead, evaporation, cleavage, and / or depolymerization of the diluent can only occur with increasing residence time of the mixture in the pyrolysis reactor and the concomitant heating of the mixture. This makes it possible to obtain a homogeneous pyrolysis product.

[0027] Within the scope of the invention, it has surprisingly been found that the addition of a diluent during pyrolysis leads to a particularly wax-rich pyrolysis residue. This is particularly advantageous in connection with the process according to the invention, since it allows an even larger amount of wax to be recovered.

[0028] The pyrolysis residue provided in step (a) of the process can, in addition to the wax and the solid, also comprise a liquid fraction. The proportion of the liquid fraction is preferably a maximum of 95% by weight, more preferably 30 to 95% by weight, in particular 50 to 88% by weight, based on the total weight of the pyrolysis residue. As the proportion of the liquid fraction decreases, at least some of the wax can dissolve more quickly in the solvent, or a smaller amount of solvent has to be added to the pyrolysis residue in order to at least partially dissolve the wax in the solvent. This can subsequently also make it easier to separate at least some of the wax from the low-solids mixture. The process can thus be made more efficient.

[0029] The pyrolysis residue provided in step (a) of the process can be obtained by pyrolyzing the plastic in a pyrolysis reactor and subsequently increasing the solids concentration of the pyrolysis residue. This can be advantageous in order to reduce the proportion of the liquid fraction of the resulting pyrolysis residue to preferably a maximum of 95% by weight, more preferably to 30 to 95% by weight, in particular to 50 to 88% by weight, based on the total weight of the pyrolysis residue. To increase the solids concentration, a separation device, preferably a hydrocyclone, can be used, which can be connected downstream of the pyrolysis reactor.

[0030] If the pyrolysis residue is obtained by pyrolyzing a plastic, a gaseous fraction can be separated from the pyrolysis residue following pyrolysis and before step (a) of the process. The gaseous fraction can be separated by evaporation, for example, in a hydrocyclone, which can be connected downstream of the pyrolysis reactor.

[0031] The separation of the gaseous fraction from the pyrolysis residue and the increase in the solids concentration of the pyrolysis residue can be carried out, for example, using a separation device or using a plurality of separation devices connected in series. Advantageously, both the separation of the gaseous fraction from the pyrolysis residue and the increase in the solids concentration of the pyrolysis residue are carried out in just one process step by means of a hydrocyclone, which can be connected downstream of the pyrolysis reactor. Such a hydrocyclone is described in the application WO 2023 / 036751 A1. By introducing a mixture comprising the pyrolysis residue and the gaseous fraction via an inlet arranged in an upper region of a jacket of the hydrocyclone, a vortex flow can be generated in the hydrocyclone, as a result of which the gaseous fraction is separated from the pyrolysis residue and passed through aon the ceiling of which) arranged outlet. The pyrolysis residue can then be carried off under gravity in the direction of a base of the hydrocyclone, it being possible for a tangential velocity of a developing vortex flow to increase continuously. As a result, at least part of the pyrolysis residue, in particular at least a part of the pyrolysis residue at least partially comprising the wax and the solid, can be carried off via an outlet arranged in the base of the hydrocyclone, while at least part of the liquid fraction of the pyrolysis residue can reach an inner container arranged in the hydrocyclone and from there be carried off via an outlet, e.g. for further use as a diluent. The pyrolysis residue carried off via the outlet arranged in the base of the hydrocyclone can then be provided according to step (a) of the process.The hydrocyclone is preferably operated at a temperature in the range of 300 to 450 ° C, more preferably from 320 to 420 ° C, particularly preferably from 360 to 400 ° C.

[0032] The pyrolysis residue can be cooled before the addition of the solvent, either before step (a) of the process, or between steps (a) and (b). The cooling can be carried out by means of a cooling unit. The pyrolysis residue is preferably cooled to a temperature of not more than 240 °C, more preferably not more than 220 °C, particularly preferably not more than 180 °C. Cooling the pyrolysis residue can be advantageous in particular when the pyrolysis residue is obtained by immediately preceding processing of a plastic (by pyrolyzing and optionally subsequently separating a gaseous fraction from the pyrolysis residue and / or increasing the solids concentration of the pyrolysis residue). By cooling the pyrolysis residue, undesired evaporation and / or decomposition of the solvent during addition to the pyrolysis residue can be reduced or completely prevented.The pyrolysis residue is preferably cooled to a temperature of not less than 80 ° C, more preferably not less than 100 ° C, particularly preferably not less than 120 ° C. If this temperature is not exceeded, this has the advantage that the solubility of the wax in the solvent is better.

[0033] The solvent can be added to the pyrolysis residue in step (b) of the process by means of an introduction device. The introduction device can have a metering device, such as a metering pump. For the addition of the solvent, the pyrolysis residue can be fed to a container to which the introduction device can be connected. The container can be heatable so that the wax can be dissolved in the solvent at a specific temperature.

[0034] The wax is preferably dissolved in the solvent at a temperature of at least 80°C, more preferably at least 100°C, even more preferably at least 120°C, even more preferably 140°C, in particular at least 160°C. The wax is preferably dissolved at a temperature in the range from 80 to 240°C, more preferably from 100 to 160°C, in particular 100 to 140°C. This ensures good process efficiency because, on the one hand, the wax can dissolve well and quickly in the solvent, and on the other hand, the process can be carried out quickly and energy-efficiently. The wax can dissolve particularly well in the solvent at a temperature of just 100 to 120°C, while a temperature of 120 to 140°C can be optimal from a process engineering perspective.

[0035] The wax can preferably be dissolved in the solvent at a pressure in the range of 1 to 25 bar, in particular in the range of 5 to 16 bar. This can further improve the process control and achieve rapid dissolution of the wax in the solvent.

[0036] The solvent can preferably have a boiling point (or a boiling range) in the range from 20 to 270°C, more preferably from 20 to 250°C, even more preferably from 35 to 255°C, even more preferably from 20 to 200°C, especially from 50 to 150°C. This allows the process to be carried out efficiently. In particular, the solvent preferably has a boiling point (or an upper end of a boiling range) that is at least 10°C, more preferably at least 30°C, especially at least 50°C, below the boiling point of the wax (or below a lower end of the boiling range of the wax). This allows the wax to be easily separated from the solids-free mixture. The boiling temperature (or boiling range) of the solvent can be determined using ASTM D5399-09 : 2017 or ASTM D2887-22 : 2022.

[0037] The solvent preferably comprises at least 10 wt.%, more preferably at least 20 wt.%, even more preferably at least 50 wt.%, even more preferably at least 70 wt.%, in particular at least 90 wt.%, of an aliphatic hydrocarbon, based on the total weight of the solvent. The solvent preferably consists of an aliphatic hydrocarbon or a mixture consisting of two or more aliphatic hydrocarbons. With an increasing proportion of aliphatic hydrocarbon, not only can the ability of the solvent to dissolve the wax improve, but the solubility of the solid in the solvent can also be reduced. With a high proportion of an aromatic compound in the solvent, however, the solid, in particular an asphaltene or tar, can dissolve well in the solvent, which can complicate the subsequent separation of the wax or can result in contaminated wax.If the solvent contains a high proportion of a cycloalkane, the wax may dissolve well, but the yield may be comparatively low.

[0038] The aliphatic hydrocarbon is preferably selected from the group of aliphatic hydrocarbons with up to 15 carbon atoms per molecule, in particular from 4 to 12 carbon atoms per molecule. This allows the process to be carried out efficiently and enables good separation of the wax from the solid mixture.

[0039] The aliphatic hydrocarbon is preferably selected from n-pentane, n-hexane, cyclohexane, n-heptane, isododecane, tetradecane, an isomer thereof, or a mixture thereof. Since the boiling point of these aliphatic hydrocarbons ranges from 35 to 255 °C, the process can be carried out efficiently and economically. Furthermore, the wax dissolves well in these solvents due to their low molecular weight. Preferably, the solvent comprises 10 to 80 wt.% of an aliphatic hydrocarbon having up to 15 carbon atoms per molecule, 10 to 40 wt.% of an isoparaffin, 10 to 40 wt.% of an n-paraffin, and 5 to 20 wt.% of an aromatic. It is particularly preferred if the solvent comprises 20 to 30 wt% of an aliphatic hydrocarbon having up to 15 carbon atoms per molecule, 20 to 30 wt% of an iso-paraffin, 20 to 30 wt% of an n-paraffin, and 10 to 15 wt% of an aromatic.This includes mixtures of two or more aliphatic hydrocarbons having up to 15 carbon atoms per molecule, two or more isoparaffins, two or more n-paraffins, and / or two or more aromatics. In this embodiment, the aliphatic hydrocarbon preferably comprises n-heptane, n-octane, n-nonane, and / or n-decane, and / or isomers thereof, the proportion of these aliphatic hydrocarbons in the solvent preferably being at least 51% by weight, more preferably at least 65% by weight, even more preferably at least 80% by weight, based on the proportion of all aliphatic hydrocarbons having up to 15 carbon atoms per molecule present in the solvent. The proportion of cycloalkanes in the solvent in this embodiment is preferably below 5% by weight, more preferably below 1% by weight, even more preferably below 0.1% by weight, based on the weight of the solvent.The solvent having the above-mentioned composition preferably has a boiling range of 25 to 200 °C, and / or a density at 15 °C of 0.70 to 0.76 g / cm. 3 This solvent is particularly well suited for dissolving the wax. The solvent with this composition can also be obtained during the pyrolysis of plastic waste and can be reused through use in the process according to the invention.

[0040] The ratio of pyrolysis residue to solvent can preferably be in the range of 3:1 to 1:5, more preferably in the range of 1:1 to 1:3. This allows the wax to dissolve in the solvent quickly and as completely as possible.

[0041] At least a portion of the solid is separated from the high-solids mixture in step (c) of the process, wherein the separation can be carried out by means of a first separation device. The at least partial separation of the solid results in a low-solids mixture. The solids concentration of the resulting low-solids mixture is preferably at most 30 wt%, more preferably at most 15 wt%, even more preferably at most 5 wt%, even more preferably at most 2 wt%, even more preferably at most 1 wt%, based on the total weight of the low-solids mixture.

[0042] The solid can be separated from the solids-rich mixture by gravimetric separation, filtration and / or centrifugal force separation. The gravimetric separation can comprise sedimentation and / or decantation. In particular, the separation can be carried out by filtration. The filtration can be carried out using a filter medium which can comprise activated carbon or bleaching earth. This allows any polar components dissolved together with the wax in the solvent (e.g. a tar or a polyphenol) to be easily separated and adsorbed by the filter medium. During filtration, even particles with an average particle size (D50) of less than 100 pm, in particular less than 50 pm, can be easily removed (determined by laser diffraction). The filtration is preferably carried out at elevated temperature.Preferably, the filtration is carried out at a temperature in the range of 80 to 350°C, more preferably 90 to 300°C, even more preferably 100 to 250°C, most preferably 150 to 180°C. It is also preferred if the filtration is carried out at a pressure of 5 bar or higher, preferably 5 to 20 bar, more preferably 10 to 20 bar. Increasing the temperature and / or reducing the pressure enables more efficient separation of the solid from the solid-rich mixture.

[0043] In a preferred embodiment, the solid is separated by sedimentation and subsequent filtration, wherein the filtration is preferably carried out at a pressure of 5 bar or higher and at a temperature in the range of 100 to 250°C, more preferably at a pressure of 10 bar or higher and at a temperature in the range of 150 to 180°C. Under these parameters, the solid can be separated particularly well from the solids-rich mixture. This separation efficiency can be further improved if the aliphatic hydrocarbon present in the solvent is n-heptane, and in particular if the solvent is n-heptane.

[0044] The solid preferably comprises an inorganic salt, a ceramic raw material, an asphaltene, a tar and / or a coke. Coke is particularly preferably present in the pyrolysis residue. This is particularly the case when the pyrolysis residue is obtained by pyrolyzing a plastic, and subsequently a liquid fraction and / or a gaseous fraction are separated from the pyrolysis residue before the pyrolysis residue is provided according to step (a) of the process. In particular, the solid can comprise talc, an iron oxide (e.g. iron (III) oxide), aluminum oxide, titanium dioxide, magnesium oxide and / or calcium carbonate. If the pyrolysis residue provided is obtained by pyrolyzing a plastic, the solid can comprise an additive contained in the plastic. For example, the additive can comprise a filler, a color pigment and / or an additive.A person skilled in the art will know which additives are used depending on the particular plastic and field of application. After being separated from the solids-rich mixture, i.e., after step (c) of the process, the solid can be dried, for example, in an oven. This makes the solid free-flowing and thus easier to process. The solid is preferably dried at a temperature in the range of 50 to 250°C, more preferably 100 to 200°C, and even more preferably 130 to 160°C. The drying time is preferably up to 120 minutes, in particular 5 to 60 minutes.

[0045] One or more components can be separated from the solid, especially from the dried solid, e.g., by filtration and / or centrifugation. Separated components can then be reused, e.g., as an additive for a plastic.

[0046] Solvent separated during drying of the solid can be reused in step (b) of the process. Before being recycled to the process, the solvent can be further purified, preferably by evaporation, in particular by rotary evaporation.

[0047] The separation of at least a portion of the wax in step (d) of the process may comprise evaporation or extraction under pressure. The temperature in step (d) is preferably in the range of 50 to 280°C, more preferably 80 to 150°C, particularly preferably 100 to 130°C. The pressure in step (d) is preferably in the range of 0.1 to 2.5 bar, preferably 0.5 to 1 bar. This allows the separation to take place as completely and quickly as possible.

[0048] If the boiling temperature (or an upper end of the boiling range) of the solvent is significantly below an extraction temperature (e.g., at least 10°C below, or at least 15°C below), the separation preferably comprises extraction under pressure, such as in a hydrocyclone. If the boiling temperature (or a lower end of the boiling range) of the solvent is above the extraction temperature, substantially equal to the extraction temperature, or just below it (e.g., up to 10°C below, or up to 15°C below), the separation preferably comprises evaporation.

[0049] After separating the wax in step (d) of the process, the solvent contained in the solid mixture can be reused in step (b). For this purpose, the solvent can be separated from the solid mixture, preferably by evaporation, in particular by rotary evaporation.

[0050] The wax separated in step (d) of the process preferably has a boiling point (or a lower end of a boiling range) of at least 280°C, more preferably at least 300°C, even more preferably at least 350°C. Preferably, the wax has a boiling point (or a boiling range) in the range of 280 to 730°C, even more preferably 350 to 700°C. The wax can then be readily separated from the solids-free mixture. The boiling point (or boiling range) of the wax can be determined using the ASTM D7500-15: 2019 standard (preferably for a wax with a boiling point or boiling range of 100 to 850 °C, in particular 100 to 735 °C) or using the ASTM D2887-22: 2022 standard (preferably for a wax with a boiling point or boiling range of 55 to 538 °C).

[0051] The separated wax preferably has at least 15 carbon atoms per molecule, more preferably at least 20, in particular at least 40. Preferably, the wax has 20 to 80 carbon atoms per molecule, in particular 20 to 65. Such waxes can be readily further used in a refinery, as a lubricant and / or as an additive.

[0052] The separated wax preferably comprises at least 0.1% by weight of the solvent, more preferably at least 5% by weight, in particular at least 10% by weight, based on the total weight of the wax. This can reduce the pour point of the wax and thus improve its pumpability. The separated wax preferably comprises a maximum of 60% by weight of the solvent, preferably a maximum of 50% by weight, more preferably a maximum of 20% by weight, based on the total weight of the wax. Otherwise, the properties of the wax may be impaired. The separated wax preferably comprises 0.1 to 50% by weight of the solvent, more preferably 0.1 to 20% by weight, based on the total weight of the wax.

[0053] The separated wax can be fed to a processing plant in a refinery, in particular a fluid catalytic cracking (FCC) plant, a steam cracker, a thermal gasoil unit (TGU plant), a hydrogenation plant and / or a coker. The wax is preferably fed to an FCC plant and / or a steam cracker. In a steam cracker, the wax can be converted into a low molecular weight alkene (or into a mixture of two or more such alkenes), in particular into ethene and / or propene. This enables reuse in the production of plastics, in particular polyolefins.

[0054] When fed to the processing plant, the wax preferably has a temperature of 40 ° C or more, preferably 50 ° C or more, more preferably 80 ° C or more, in particular 100 ° C or more; preferably the temperature is from 40 ° C to 300 ° C, preferably from 50 ° C to 280 ° C, even more preferably from 80 to 200 ° C, even more preferably from 100 to 180 ° C. Solidification of the wax can then be avoided. This can also be advantageous for energy reasons if the separation of at least part of the wax from the low-solids mixture already takes place at an elevated temperature, and an elevated temperature is also required in the processing plant, because then the already heated wax can be fed to the processing plant without prior cooling and, if appropriate, with further heating.The separated wax can also be used in other technical fields, for example, as a lubricant and / or additive. The separated wax can be processed before further use. For example, the wax can be purified and / or separated into different carbon fractions.

[0055] Preferably, the separated wax is mixed with a hydrocarbon stream before being fed to a processing plant in a refinery, in particular an FCC plant. The hydrocarbon stream preferably comprises a gas oil, preferably a vacuum gas oil (VGO) and / or a visbreaker gas oil. The hydrocarbon stream preferably has a boiling temperature (or a lower end of a boiling range) of 100°C or above, more preferably 150°C or above, even more preferably 200°C or above. It is particularly preferred if the hydrocarbon stream has a boiling temperature (or a boiling range) in the range from 100 to 400°C, more preferably from 150 to 300°C, even more preferably from 150 to 200°C. This can result in optimal rheological properties for further processing of the mixture of wax and hydrocarbon stream. The boiling temperature (orThe boiling point (or boiling range) of the hydrocarbon stream can be determined using the ASTM D7500-15:2019 standard (preferably for a hydrocarbon stream with a boiling temperature or boiling range of 100 to 850 °C, in particular 100 to 735 °C) or using the ASTM D2887-22:2022 standard (preferably for a hydrocarbon stream with a boiling temperature or boiling range of 55 to 538 °C). Preferably, the hydrocarbon stream has a similar number of carbon atoms per molecule as the separated wax (e.g. a number of 10 carbon atoms or more per molecule). The wax can then be well mixed with the hydrocarbon stream.The mixture of wax and hydrocarbon stream preferably contains an amount of wax of 50 wt% or less, more preferably 20 wt% or less, even more preferably 10 wt% or less, particularly preferably 5 wt% or less, in particular 2 wt% or less, based on the total weight of the mixture. The mixture particularly preferably contains an amount of wax of 0.1 to 2 wt%, based on the total weight of the mixture. This not only enables the separated wax to be upgraded, but the mixing of the wax with the hydrocarbon stream also ensures constant process conditions in the processing plant of the refinery, in particular the FCC plant.

[0056] The invention also relates to a device for obtaining a wax from the pyrolysis residue using the method according to the invention, comprising an introduction device for adding the solvent to the pyrolysis residue, a first separation device for separating at least part of the solids from the solids-rich mixture, and a second separation device for separating at least part of the wax from the solids-poor mixture, preferably wherein a cooling unit (11) for cooling the pyrolysis residue before the addition of the solvent is arranged upstream of the introduction device (14). The introduction device for adding the solvent can have a metering device, such as a metering pump.

[0057] The introduction device can be connected to a container into which the pyrolysis residue can be fed, so that the wax can be dissolved in the solvent in this container. The container can be heated so that the wax can be dissolved in the solvent at an elevated temperature.

[0058] The first separation device may comprise a gravimetric separation device, a filter, a cyclone, a hydrocyclone or a combination thereof, preferably a filter.

[0059] The second separation device may comprise an evaporator and / or an extraction device.

[0060] The device may further comprise a dryer, such as an oven, in particular a vacuum oven, in order to dry the solid after its separation, i.e. after step (c).

[0061] The invention further relates to a device for obtaining a wax from a plastic, in particular a waste plastic, comprising the aforementioned device (for obtaining a wax from the pyrolysis residue) and a pyrolysis reactor for pyrolyzing the plastic in order to obtain the pyrolysis residue.

[0062] The device may further comprise a mixer, in particular an extruder, to plasticize the plastic before adding it to the pyrolysis reactor.

[0063] The device may also comprise an addition device for adding a diluent to the plastic and thereby reducing its viscosity, wherein the addition device is arranged upstream of the pyrolysis reactor. If the device comprises an extruder, the addition device may be arranged downstream of the extruder or directly on the extruder, in particular in its compression zone or mixing zone. Alternatively, the device may comprise a mixer, in particular a static mixer, for mixing the plastic, in particular the plasticized plastic, with the diluent. The invention relates in particular to the following embodiments:

[0064] 1. A process for obtaining a wax from a pyrolysis residue, comprising the steps

[0065] (a) providing the pyrolysis residue, wherein the pyrolysis residue comprises the wax and a solid, preferably wherein the solid comprises an inorganic salt, a ceramic raw material, an asphaltene, a tar and / or a coke,

[0066] (b) adding a solvent to the pyrolysis residue to obtain a solids-rich mixture comprising the solid and the solvent, wherein the wax is at least partially dissolved in the solvent,

[0067] (c) separating at least a portion of the solid from the solid-rich mixture to obtain a solid-lean mixture, and

[0068] (d) separating at least a portion of the wax from the low-solids mixture.

[0069] 2. The process according to embodiment 1, wherein the solvent has a boiling temperature in the range from 20 to 270 °C, preferably from 20 to 250 °C, more preferably from 35 to 255 °C, in particular from 50 to 150 °C.

[0070] 3. The process according to embodiment 1 or 2, wherein the solvent comprises at least 10 wt%, preferably at least 20 wt%, more preferably at least 50 wt%, even more preferably at least 70 wt%, in particular at least 90 wt%, of an aliphatic hydrocarbon, based on the total weight of the solvent.

[0071] 4. The process according to embodiment 3, wherein the aliphatic hydrocarbon is selected from the group of aliphatic hydrocarbons having up to 15 carbon atoms per molecule, preferably from 4 to 12 carbon atoms per molecule.

[0072] 5. The process according to embodiment 4, wherein the aliphatic hydrocarbon is selected from n-pentane, n-hexane, cyclohexane, n-heptane, isododecane, tetradecane, an isomer thereof, or a mixture thereof.

[0073] 6. Process according to one of embodiments 1 to 5, wherein the ratio of pyrolysis residue to solvent is in the range from 3:1 to 1:5, preferably in the range from 1:1 to 1:3.

[0074] 7. The process according to any one of embodiments 1 to 6, wherein in step (b) the dissolution of the wax in the solvent takes place at a temperature of at least 80 °C, preferably at least 100 °C, more preferably at least 120 °C, even more preferably at least 140 °C, in particular at least 160 °C, particularly preferably in the range from 80 to 240 °C, more preferably from 100 to 160 °C, in particular 100 to 140 °C.

[0075] 8. Process according to one of embodiments 1 to 7, wherein in step (b) the dissolution of the wax in the solvent takes place at a pressure in the range of 1 to 25 bar, preferably in the range of 5 to 16 bar.

[0076] 9. Process according to one of embodiments 1 to 8, wherein the solid is separated in step (c) by gravimetric separation (in particular sedimentation), filtration and / or centrifugal separation, preferably by filtration.

[0077] 10. The process according to embodiment 9, wherein the solid in step (c) is separated by filtration, preferably by sedimentation and subsequent filtration; preferably wherein the filtration is carried out at a temperature in the range of 80 to 350 °C, more preferably 90 to

[0078] 300°C, more preferably from 100 to 250°C, most preferably from 150 to 180°C; and / or at a pressure of 5 bar or more, preferably from 5 to 20 bar, more preferably from 10 to 20 bar.

[0079] 11. Process according to one of embodiments 1 to 10, wherein the solid is dried after step (c), preferably at a temperature of 50 to 250 °C, more preferably 100 to 200 °C, in particular 130 to 160 °C, and / or for a period of up to 120 min, preferably 5 to 60 min.

[0080] 12. The process according to embodiment 11, wherein solvent separated during drying of the solid is reused in step (b).

[0081] 13. The process according to any one of embodiments 1 to 12, wherein the separation of at least a portion of the wax in step (d) comprises evaporation or extraction under pressure.

[0082] 14. The process according to embodiment 13, wherein the temperature is in the range from 50 to 280 °C, more preferably from 80 to 150 °C, particularly preferably from 100 to 130 °C, and / or wherein the pressure is in the range from 0.1 to 2.5 bar, more preferably from 0.5 to 1 bar.

[0083] 15. The process according to any one of embodiments 1 to 14, wherein solvent contained in the solids-free mixture after step (d) is reused in step (b).

[0084] 16. The process according to any one of embodiments 1 to 15, wherein the separated wax has a boiling temperature of at least 280 °C, preferably at least 300 °C, more preferably at least 350 °C, wherein the separated wax preferably has a boiling temperature in the range of 280 to 730 °C, more preferably of 350 to 700 °C.

[0085] 17. The process according to any one of embodiments 1 to 16, wherein the separated wax has at least 15 carbon atoms per molecule, preferably at least 20, in particular at least 40, wherein the wax preferably has 20 to 80 carbon atoms per molecule, in particular 20 to 65.

[0086] 18. The process according to any one of embodiments 1 to 17, wherein the wax separated in step (d) comprises at least 0.1 wt% of the solvent, more preferably at least 5 wt%, even more preferably at least 10 wt%, and / or wherein the separated wax comprises a maximum of 60 wt% of the solvent, preferably a maximum of 50 wt%, more preferably a maximum of 20 wt%, based on the total weight of the wax.

[0087] 19. The process according to embodiment 18, wherein the separated wax comprises 0.1 to 50 wt% of the solvent, more preferably 0.1 to 20 wt%, based on the total weight of the wax.

[0088] 20. Process according to one of embodiments 1 to 19, wherein the pyrolysis residue is obtained by pyrolyzing a plastic, in particular a waste plastic.

[0089] 21. The process according to embodiment 20, wherein the pyrolysis residue is obtained by pyrolyzing the plastic in a pyrolysis reactor and subsequently increasing the solids concentration of the pyrolysis residue. 22. The process according to embodiment 20 or 21, wherein the pyrolysis residue comprises a liquid fraction, the proportion of the liquid fraction preferably being at most 95 wt%, more preferably in the range from 30 to 95 wt%, in particular from 50 to 88 wt%, based on the total weight of the pyrolysis residue.

[0090] 23. Process according to any one of embodiments 20 to 22, wherein the pyrolysis residue is cooled before step (b), preferably to a temperature of not more than 260 °C, more preferably not more than 220 °C, particularly preferably not more than 180 °C, and / or preferably to a temperature of not less than 80 °C, more preferably not less than 100 °C, particularly preferably not less than 120 °C.

[0091] 24. The process according to any one of embodiments 1 to 23, wherein the separated wax is fed to a processing plant of a refinery, in particular an FCC plant and / or a steam cracker; preferably wherein the wax, upon feeding to the processing plant, has a temperature of 40°C or above, preferably 50°C or above, more preferably 80°C or above, in particular 100°C or above; or a temperature of 40°C to 300°C, preferably from 50°C to 280°C, even more preferably from 80 to 200°C, even more preferably from 100 to 180°C.

[0092] 25. The method according to embodiment 24, wherein the separated wax is mixed with a hydrocarbon stream before being fed to the processing plant, in particular FCC plant; wherein the hydrocarbon stream preferably has a boiling temperature (or a lower end of a boiling range) of 100 °C or above, more preferably of 150 °C or above, even more preferably of 200 °C or above; and / or wherein a mixture of the wax and the hydrocarbon stream preferably contains an amount of the wax of 50 wt% or below, more preferably

[0093] 20 wt% or less, more preferably 10 wt% or less, particularly preferably 5 wt% or less, in particular 2 wt% or less, based on the total weight of the mixture.

[0094] 26. Device for obtaining a wax from a pyrolysis residue using the method according to one of embodiments 1 to 25, comprising an introduction device for adding the solvent to the pyrolysis residue, and a first separation device for separating at least part of the solid from the solid-rich mixture, and a second separation device for separating at least part of the wax from the solid-poor mixture, preferably wherein a cooling unit (11) for cooling the pyrolysis residue before the addition of the solvent is arranged upstream of the introduction device (14).

[0095] 27. Device according to embodiment 26, wherein the introduction device has a dosing device, in particular a dosing pump.

[0096] 28. Apparatus according to embodiment 26 or 27, wherein the first separation device comprises a gravimetric separation device, a filter, a cyclone, a hydrocyclone or a combination thereof, preferably a filter.

[0097] 29. Device according to one of embodiments 26 to 28, wherein the second separation device comprises an evaporator and / or an extraction device.

[0098] 30. Device for obtaining a wax from a plastic, in particular a waste plastic, comprising the device according to one of the embodiments 26 to 29 and a pyrolysis reactor for pyrolyzing the plastic to obtain the pyrolysis residue.

[0099] 31. Apparatus according to embodiment 30, further comprising a mixer, preferably an extruder, to plasticize the plastic before adding it to the pyrolysis reactor.

[0100] 32. Device according to embodiment 30 or 31, further comprising an addition device for adding a diluent to the plastic, wherein the addition device is arranged upstream of the pyrolysis reactor.

[0101] The invention is further explained below with reference to figure descriptions of some embodiments, to which, however, the invention is not limited.

[0102] Fig. 1 shows a flow diagram of a pyrolysis process in which wax is obtained from a pyrolysis residue.

[0103] As can be seen from Fig. 1, a plastic comprising at least 50 wt.% of a polyolefin is fed to an extruder 1, in which the plastic is plasticized and degassed. The plasticized plastic has a temperature of at least 120°C and is then fed to a static mixer 2. In the static mixer 2, a diluent 3 can be added to the plasticized plastic in order to reduce its viscosity. Alternatively or in addition to the diluent 3, a portion of a liquid fraction 4 separated from a pyrolysis residue can be mixed with the plasticized plastic in order to reduce its viscosity. The resulting mixture is then fed to a pyrolysis reactor 5, in which the plastic is pyrolyzed at a temperature of 350 to 450°C. This produces a pyrolysis product 6 comprising a gaseous fraction, a liquid fraction, a wax, and a solid.The pyrolysis product 6 is fed to a hydrocyclone 7 downstream of the pyrolysis reactor 5. First, the gaseous fraction is at least partially separated in the hydrocyclone 7. The separated part of the gaseous fraction 8 can then be further separated into a light oil (e.g. with a boiling range of 35 to 225 °C) and a heavy oil (e.g. with a boiling range of 225 to 410 °C) (not shown). Furthermore, the liquid fraction is at least partially separated in the hydrocyclone 7. The separated part of the liquid fraction 4 can be discharged via an outlet 9 of the hydrocyclone 7 and reused in the process for reducing the viscosity of the plastic, as described above. At least a portion of the pyrolysis residue, which at least partially comprises the wax and the solid, is discharged via an outlet 10 arranged in the bottom of the hydrocyclone 7.

[0104] As can also be seen in Fig. 1, the pyrolysis residue discharged via outlet 10 is fed to a cooling unit 11 for cooling to a temperature in the range of 80 to 240 °C. A solvent 13 comprising at least 20 wt% of an aliphatic hydrocarbon is then added to the pyrolysis residue in a container 12 by means of an introduction device 14 in order to obtain a solids-rich mixture. The aliphatic hydrocarbon is selected from the group of aliphatic hydrocarbons having 4 to 12 carbon atoms per molecule. The resulting solids-rich mixture has a pyrolysis residue to solvent ratio in the range of 1:1 to 1:3. The container 12 is heated so that dissolution can take place at a temperature in the range of 80 to 240 °C.In a first separation device 15, which comprises a filter, the solid is at least partially separated from the solid-rich mixture in order to obtain a low-solids mixture. The separated solid 16 is then dried in an oven 17 at a temperature in the range of 100 to 200 °C. Individual components can then be separated from the solid and reused (not shown). The low-solids mixture is fed to a second separation device 18, which has an evaporator, in order to at least partially separate the wax by means of evaporation. The evaporation takes place at a temperature in the range of 80 to 150 °C and a pressure of 0.5 to 1 bar. The separated wax 19 can then be fed for further use.At least a portion of the solvent is subsequently separated from the solids-free mixture in an evaporator 20 and reused in step (b) of the process by being returned to the container 12 via the introduction device 14.

Claims

Patent claims:

1. A process for obtaining a wax from a pyrolysis residue, comprising the steps (a) providing the pyrolysis residue, wherein the pyrolysis residue comprises the wax and a solid, and wherein the solid comprises an inorganic salt, a ceramic raw material, an asphaltene, a tar and / or a coke, (b) adding a solvent to the pyrolysis residue to obtain a solids-rich mixture comprising the solid and the solvent, wherein the wax is at least partially dissolved in the solvent, (c) separating at least a portion of the solid from the solid-rich mixture to obtain a solid-lean mixture, and (d) separating at least a portion of the wax from the low-solids mixture.

2. The process of claim 1, wherein the solvent comprises at least 20% by weight of an aliphatic hydrocarbon, based on the total weight of the solvent.

3. The process according to claim 2, wherein the aliphatic hydrocarbon is selected from the group of aliphatic hydrocarbons having up to 15 carbon atoms per molecule, preferably from 4 to 12 carbon atoms per molecule.

4. The process according to claim 3, wherein the aliphatic hydrocarbon is selected from n-pentane, n-hexane, n-heptane, isododecane, tetradecane or a mixture thereof.

5. A process according to any one of claims 1 to 4, wherein in step (b) the wax is dissolved in the solvent at a temperature of at least 80°C.

6. The process according to any one of claims 1 to 5, wherein the solid is separated in step (c) by sedimentation and subsequent filtration.

7. The process according to claim 6, wherein the filtration is carried out at a temperature in the range of 100 to 250 °C and a pressure of 5 bar or more. Method according to one of claims 1 to 7, wherein the solid Fabric is dried after step (c).

9. A process according to any one of claims 1 to 8, wherein the separation of at least a portion of the wax in step (d) comprises evaporation or extraction under pressure.

10. A process according to any one of claims 1 to 9, wherein solvent contained in the solid mixture after step (d) is reused in step (b).

11. A process according to any one of claims 1 to 10, wherein the separated wax has a boiling temperature of at least 280 °C.

12. A process according to any one of claims 1 to 11, wherein the wax separated in step (d) comprises at least 0.1% by weight of the solvent.

13. The method according to any one of claims 1 to 12, wherein the pyrolysis residue is obtained by pyrolyzing a plastic, in particular a waste plastic.

14. Apparatus for obtaining a wax from a pyrolysis residue using the method according to one of claims 1 to 13, comprising an introduction device (14) for adding the solvent to the pyrolysis residue, and a first separation device (15) for separating at least part of the solid from the solid-rich mixture, and a second separation device (18) for separating at least part of the wax from the solid-poor mixture, wherein a cooling unit (11) for cooling the pyrolysis residue before the addition of the solvent is arranged upstream of the introduction device (14).

15. Device for obtaining a wax from a plastic, in particular a waste plastic, comprising the device according to claim 14 and a pyrolysis reactor (5) for pyrolyzing the plastic in order to obtain the pyrolysis residue.

Images